ELEMENTAL COMPOSITIONS OF TWO EXTRASOLAR ROCKY PLANETESIMALS
ELEMENTAL COMPOSITIONS OF TWO EXTRASOLAR ROCKY PLANETESIMALS
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DOI：
10.1088/0004-637x/783/2/79
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
Siyi Xu;M. Jura;D. Koester;B. Klein;B. Zuckerman
中科院分区：
文献类型：
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作者：
Siyi Xu;M. Jura;D. Koester;B. Klein;B. Zuckerman
我们报道了Keck/HiRes和哈勃太空望远镜/COS对两颗氢大气白矮星G29-38和GD133上附着的太阳系外岩石小行星的光谱研究。在G29-38中检测到8种元素，包括C、O、镁、硅、钙、钛、铬和铁，而在G133中检测到O、Si、Ca和少量的镁。这两个太阳系外行星体显示出一种难解增强和挥发分耗尽的模式。对于G29-38，观测到的成分可以最好地解释为软骨状物体与一些富含耐火材料的物质的混合物，这是星云后处理的结果。根据得到的氧气丰度，附着在G29-38上的母体中的水非常耗尽。GD133的总质量吸积率是所有已知尘埃白矮星中最低的，可能是由于非稳态吸积所致。我们继续发现，各种太阳系外的行星体都类似于块状地球的零级元素组成。
We report Keck/HIRES and Hubble Space Telescope/COS spectroscopic studies of extrasolar rocky planetesimals accreted onto two hydrogen atmosphere white dwarfs, G29-38 and GD 133. In G29-38, eight elements are detected, including C, O, Mg, Si, Ca, Ti, Cr, and Fe while in GD 133, O, Si, Ca, and marginally Mg are seen. These two extrasolar planetesimals show a pattern of refractory enhancement and volatile depletion. For G29-38, the observed composition can be best interpreted as a blend of a chondritic object with some refractory-rich material, a result from post-nebular processing. Water is very depleted in the parent body accreted onto G29-38, based on the derived oxygen abundance. The inferred total mass accretion rate in GD 133 is the lowest of all known dusty white dwarfs, possibly due to non-steady state accretion. We continue to find that a variety of extrasolar planetesimals all resemble to zeroth order the elemental composition of bulk Earth.